Owing to its huge panel and ribs, a conventional large size sun shading suspensory umbrella used in a beach environment or the like is difficult to control its stretch and closure, so it becomes the key point of using and the selection of umbrella. Various of stretch and closure structures of umbrella are available in the umbrella making field, but all existing structures of hand cranking device are in a model of ratchet and pawl. The solution of the stretch and closure structures of umbrella is mainly laid to frictional force. There are many defects in said existing structures, such as 1. frictional force is insufficient or not stable, resulting in disengagement or retroflexion in the stretching of sun shading umbrella; 2. frictional force made the abrasion of the parts, impacting its service life; 3. it is heavy and hard to stretch sun shading umbrella by cranking. 4. sometimes umbrella can not be complete contracted and closed by gravity. The present invention intends to provide a convenient stretch and closure structure of sun shading suspensory umbrella to overcome the disadvantages of conventional structure of umbrella.